Turbine blade shroud fastening



April 1943' J. K. MOSSER 2,315,642

TURBINE BLADE SHROUD FASTENING l Ml WITNESSES: F7 C 5' 0 INVENTOR dnMEs K.M ssE-R.

J BY a (75W ATTORNEY Patented Apr. 6, 1943 UNITED STATES PATENT OFFICE.

TURBINE BLADE SHROUD FASTENING Pennsylvania Application January 16, 1942, Serial No. 426,947

3 Claims.

The invention relates to a row of turbine blades having individual and integral shroud elements arranged circumferentially in end-to-end relation to form a shroud construction for the blade passages and it has for an object to provide arcuate tie bands disposed within the confines of the inner and outer surfaces of the shroud elements for connecting the blades circumferentially in groups.

A further object of the invention is to provide a row of turbine blades having shroud elements whose ends are in contiguous relation and which have circumferential groove or grooves formed at one or both sides of the shroud elements with arcuate tie bands in each groove and fastened to the shroud elements so as to connect the blades circumferentially in groups.

A further object of the invention is to provide turbine blades having shroud elements arranged circumferentially in end-to-end relation and to connect the latter by means of arcuate tie bands disposed in grooves 'at the sides of the shroud elements, fastened to the latter, and formed to provide clearance spaces bridging contiguous end corners of the shroud elements of each group.

These and other objects are effected by the invention as will be apparent from the following decription and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a fragmentary view, partly in section and partly in elevation and showing the improved shroud construction applied to turbine blades;

Fig. 2 is a fragmentary plan view looking down on the shroud construction of Fig. 1;

Fig. 3 is an elevational view of a blade showing the shroud construction in section and the relation of the latter with respect to the housing structure; and,

Figs. 4 and 5 are detail views showing a modified form of tie band construction.

In the drawing, the turbine blades ID are connected to the rotor H and are provided with a shroud construction, at [2.

Each blade comprises a root element 13, a blade element l4 and a shroud element 15. The root and shroud elements l3 and I5 of a row are arranged circumferentially in end-to-end relation to provide inner and outer boundaries for the blade passages.

The shroud construction, at I2, is provided by the shroud elements IS, the tie bands or strips I6 and the pins I! for connecting the strips to the shroud elements.

The circular arrangement of shroud elements I5 of each blade row is formed with relatively deep circular channels l8 for the strips [6, whereby there may be provided strips of adequate strength without excessive radial thickness.

With the construction so far described, it will be apparent that the tie bands are arranged entirely within the boundary of the section of a shroud element. Therefore, it is possible to connect the blades in groups with the preservation of seal strips 20 carried by the cylinder 2| and cooperating with the peripheral surface of the:

shroud construction.

To provide clearance spaces avoiding contact of adjacent shroud element corners with the tie.

band, thereby facilitating manufacture and as sembly and minimizing stress concentration at av section of the tie band radially aligned with the.-

corners and due to centrifugal or vibratory effects, in Figs. 4 and 5, each tie band [6a has relatively wide and shallow concave grooves 23 formed in the inner and outer faces thereof and which bridge the contiguous corners of the shroud elements.

While I have shown the invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What is claimed is:

1. In a turbine, a row of moving blades defining blade passages, a shroud construction covering the blade passages and comprising shroud elements integral with the respective blades and disposed circumferentially in end-to-end relation, said shroud elements each being recessed so as to provide a circumferential space open to one side of the shroud construction, a tie band construction comprising a plurality of tie bands disposed in end-to-end relation in said space, and means for fastening the tie bands to each of the shroud elements so as to connect the blades in circumferential groups, one of said constructions being recessed so as to provide clearance spaces between the tie bands and the shroud elements and which extend for substantial distances laterally of the adjacent inner edges of the contiguous shroud element ends to bridge the latter.

2. In a turbine, a row of moving blades defining blade passages, a shroud construction covering the blade passages and comprising shroud elements integral with the respective blades and disposed circumferentially in end-to-end relation,

said shroud construction having a lateral groove, tie bands disposed circumferentially in end-toend relation in the groove, means for fastening the ti bands to each of the shroud elements to connect the blades in groups, said shroud elements and the bands being constructed and arranged to provide clearance spaces between the tie bands and the shroud elements and which extend for substantial distances laterally of the adjacent inner edges of the contiguous shroud element ends to bridge the latter.

3. In a turbine, a row of moving blades defining ments integral with the respective blades and dis posed circumferentially in end-to-end relation,

said shroud construction having grooves at either side and opening laterally thereof, each groove being of greater depth than width, a plurality of strips disposed circumferentially in end-to-end relation in each groove, each strip being of a section conforming approximately to that of its groove, means for fastening the strips to each of the shroud elements so as to connect the blades in groups, and said strips having relatively wide and shallow grooves formed in the inner and outer faces thereof and which extend for substantial distances laterally of the adjacent inner edges of the contiguous shroud element ends to bridge the latter.

JAMES K. MOSSER. 

